The germinative cells of oral mucosa and epidermis differentiate into spinous, granular and keratinized cells sequentially. Keratohyalin granules (KHG) are a distinctive component of the granular layer, but the fully keratinized cells contain only filamentous proteins embedded in a matrix. The aim of this proposal is to determine the role of keratohyalin in normal keratinization in mammalian oral mucosa and epidermis. Morphologic studies of previous investigators suggested that KHG may be a precursor of the interfilamentous matrix of keratin. A prominent nonfilamentous basic protein has been isolated from the keratinized epidermis of newborn rats which has biochemical properties similar to a component of KHG. Labeling studies with histidine have led to the postulate that a KHG protein of high molecular weight is broken down to become the final product identified in the keratinized cells. Antibody to the basic protein will be used in further tests of the relationship of KHG and keratinized cell proteins using analytical techniques and other immunologic techniques at the light and electron microscopic level. KHG differ in their appearance in skin and oral mucosa. Do these differences reflect differences in the biochemistry of keratinization? Can these differences be related to differences in function of the various epithelia? Biochemical and immunologic studies of oral tissues will answer these questions. BIBLIOGRAPHIC REFERENCES: Dale, B.A., and Ling, S-Y. 1977. Derivation of a basic stratum corneum protein from keratohyalin. Clin. Res., 75:197A. Dale, B.A., and Clagett, J. 1976. Stratum corneum proteins of oral epithelium. J. Dent. Res., 55:B66.